Our lab has several interests related to the mechanisms involved with membrane fusion, synaptic transmission, and synaptic plasticity:

•Nanomechanics of Ca2+-triggered membrane fusion. These studies involve the analysis of a number of Ca2+-binding proteins (synaptotagmin, Doc2, Otoferlin, Rabphilin, etc.), as well as a number of other accessory proteins (nSec1, complexin, munc13, etc.) that regulate the core of the fusion apparatus - the SNARE complex - to control fusion reactions. We employ a diverse range of research tools to study membrane fusion including biophysical (electrophysiology, imaging etc.) and time-resolved biochemical (reconstituted fusion, stopped-flow kinetics, SPR, ITC etc.) techniques. Using these methods we are able to relate the function of individual proteins in in vitro systems with their function(s) in living neurons and in neuronal circuits.

•How changes in the membrane fusion machinery underlie aspects of synaptic plasticity.Using electrophysiological approaches and modern microscopy approaches (confocal, TIRF, 2-photon etc.) we are reconstituting and studying simple synaptic circuits to further our understanding of how connectivity impacts synaptic transmission, and to study the phenotypes exhibited by neurons cultured from genetically modified mice. We also study slice preparations from genetically modified mice to address the role of membrane trafficking proteins in synaptic plasticity, including long term potentiation.

•Structure and function of fusion pores. The first aqueous connection between the lumen of a secretory vesicle and the extracellular space is called the fusion pore. The structure of of the pore is the subject of debate, with some evidence that the pore might be composed of the membrane anchors of SNARE proteins while others argue the pore is purely lipidic. We study the structure and dynamics of fusion pores in neuroendocrine cells using carbon fiber amperometry and in neurons using optical approaches with single vesicle resolution. In our view, synaptic vesicle exocytosis often involves a kiss-and-run mechanism in which open fusion pores close without dilating to give rise to full fusion and bilayer merger.